SageBrush wrote:
Because they find they do not "need" it, and the rinky-dink part sits unused.
Much better that way than to invest the R&D required for a spiffy part that is expensive and then rarely bought and even less often used.

Seems like it would work the other way, for a rinky-dink afterthought - most people would only choose to buy it after finding they need it, whereas a retracting sunshade would most likely be built-into the car. It's not as if Tesla doens't bundle unwanted options with desired ones: having to pay $5k for A/P just to get ACC being a case in point.

That makes it much worse -- force everybody to pay for a part that few care about.

Sure it's worse assuming that it can't be added afterwards, but that's exactly what every automaker (including Tesla) does, to boost their profit margin. The ideal would be to offer it and every other option a la carte.

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.

Good turnout and conversation at EV Breakfast yesterday, Aug 5. In addition to all the discussion about Model 3, there was quite a bit of interest in the Eclipse Mon Aug 21. Jason is going to OR, Sparky, Mark Z, and myself are going to ID. May we all have good clear weather, clouds not allowed.

At the previous breakfast, talking about the eclipse, some opinion was expressed that the Earth's axial rotation was the dominant factor in the speed that the Moon's shadow moves across the country. I was skeptical, so I put on my physicist's hat. My calculations are rough, taking some approximations to keep math simple and avoid 3D vectors which are hard to visualize:

We choose a reference frame centered on the Earth-Moon system, so we can ignore their common motion about the sun, which is almost 100 10^6 miles/hr relative to the Sun. One Lunar month, new Full Moon to next Full Moon, is called the Synodic Period.

If we look down on the system at Eclipse from above the North pole, we see the Sun, Moon and Earth all in a line, with both the Moon's orbital motion and the Earth's rotation counterclockwise. Note, at this time, the Earth's spin and Moon's motion are in the same approximate direction, so the Earth's spin reduces the speed at which the Moon's shadow moves across the surface. We apply some correction factors to both speeds:

Because the Earth is farther from the Sun than the Moon at a New Moon, the speed of the Lunar shadow is amplified by the ratio of their distances (in 10^6 miles):
(98 + .25)/98 but we can ignore this.

The local latitude determines how far one is away from the Earth's axis, and hence how much speed you have from the spin. It does not affect the Lunar speed. Latitude(Rexburg, ID) = 44 deg,
Cos(44 deg) = .72

Finally, there is the local time of day. If the sun is not directly overhead, the shadow will be elongated by its projection on the surface, an enlargement of 1/Cos(angle from zenith). The speed of the shadow along the surface will be affected by east-west tilt, but not north-south tilt.

Note: This coming Aug 19th, the HTB Gathering will be the last in our 7th
year of Gatherings. Three weeks later, skipping the holiday weekend on
September 2nd, we begin our 8th year of Gatherings on Sep 9th at the GC.